For numerous mechanical and electromechanical applications it is necessary to determine the angular position of a shaft for control and other purposes. Conventional techniques for such shaft position determination have included the use of magnetic pick-ups, the combination of a light source with a tachometer wheel and an interdigitated series of light sensors, and various arrangements featuring the combination of a fixed light polarizer interacting with a polarized plate rotating coaxially with the shaft. While each of these techniques has performed satisfactorily in various applications, such apparatus has generally been bulky and complex and overly expensive.